Managing Image Presets

Image Presets enable AEM Assets to dynamically deliver images at different sizes, in different formats, or with other image properties there are generated dynamically. Each Image Preset represents a predefined collection of sizing and formatting commands for displaying images. When you create an Image Preset, you choose a size for image delivery. You also choose formatting commands so that the appearance of the image is optimized when the image is delivered for viewing.

Administrators can create presets for exporting assets. Users can choose a preset when they export images, which also reformats images to the specifications that the administrator specifies.

You can also create image presets that are responsive. If you apply a responsive image preset to your assets, they change depending on the device or screensize they are viewed on.

This section describes how to create, modify, and generally manage image presets. You can apply an image preset to an image anytime you preview it. See Applying Image Presets.

Примітка.

You can also configure image presets to use CMYK in the color space in addition to RGB or Gray if you have the following feature pack for dynamic media color management installed:

Understanding Image Presets

Like a macro, an Image Preset is a predefined collection of sizing and formatting commands saved under a name. To understand how Image Presets work, suppose your web site requires each product image to appear in different sizes, different formats, and compression rates for desktop and mobile delivery.

You could create two image presets: one with 500 x 500 pixels for desktop version and 150 x 150 pixels for the mobile version. You create two Image Presets, one called Enlarge to display images at 500x500 pixels and one called Thumbnail to display images at 150 x 150 pixels. To deliver images at the Enlarge and Thumbnail size, AEM looks up the definition of the Enlarge Image Preset and Thumbnail Image Preset. Then AEM dynamically generates an image at the size and formatting specifications of each Image Preset.

Images that are reduced in size when they are delivered dynamically can lose sharpness and detail. For this reason, each Image Preset contains formatting controls for optimizing an image when it is delivered at a particular size. These controls make sure that your images are sharp and clear when they are delivered to your web site or application.

Administrators can create Image Presets. To create an image preset, you can start from scratch or you can start from an existing one and save it under a new name.

Managing Image Presets

You manage your image presets in AEM by tapping or clicking the AEM logo to access the global navigation console and then tapping or clicking the Tools icon and navigating to Assets > Image Presets.

Примітка.

Any image presets you create are also available as dynamic renditions when you preview assets. To deliver or preview image presets, they must be published first. See Publishing Image Presets.

Adobe Illustrator (AI), Postscript (EPS), and PDF file formats

If you intend to support the ingestion of AI, EPS, and PDF files so that you can generate dynamic renditions of these file formats, you may want to review the following information before you create image presets.

Adobe Illustrator's file format is a variant of PDF. The main differences, in the context of AEM Assets, is the following:

Adobe Illustrator documents consist of a single page with multiple layers. Each layer is extracted as a PNG sub-asset under the main Illustrator asset.

PDF documents consist of one or more pages. Each page is extracted as a single page PDF sub-asset under the main multi-page PDF document.

The sub-assets are created by the Create Sub Asset process component within the overall DAM Update Asset workflow. To see this process component within the workflow, tap Tools > Workflow > Models > DAM Update Asset > Edit.

You can view the sub-assets or the pages when you open the asset, tap the Content menu, and select Subassets or Pages. The sub-assets are real assets. That is, PDF pages are extracted by the Create Sub Asset workflow component. They are then stored as page1.pdf, page2.pdf, and so on below the main asset. After they are stored, the DAM Update Asset workflow processes them.

To use Dynamic Media to preview and generate dynamic renditions for AI, EPS or PDF files, the following processing steps are required:

In the DAM Update Asset workflow, the Rasterize PDF/AI Image Preview Rendition process component rasterizes the first page of the original asset--using the configured resolution--into a cqdam.preview.png rendition.

The cqdam.preview.png rendition is then optimized into a PTIFF by the Dynamic Media Process Image Assets process component within the workflow.

Rasterize PDF/AI Image Preview Rendition options

List of document mime-types that are considered to be PDF or Illustrator documents.

Max Width

2048

Maximum width of the generated preview rendition, in pixels.

Max Height

2048

Maximum height of the generated preview rendition, in pixels.

Resolution

72

Resolution to rasterize the first page, in ppi (pixels per inch).

Using the default process arguments, the first page of a PDF/AI document is rasterized at 72 ppi and the generated preview image is sized at 2048 x 2048 pixels. For a typical deployment, you may want to increase the resolution to a minimum of 150 ppi or more. For example, a US letter size document at 300 ppi requires a maximum width and height of 2550 x 3300 pixels, respectively.

Max Width and Max Height limit the resolution at which to rasterize. For example, if the maximums are unchanged, and Resolution is set to 300 ppi, a US Letter document is rasterized at 186 ppi. That is, the document is 1581 x 2046 pixels.

The Rasterize PDF/AI Image Preview Rendition process component has a maximum defined to ensure that it does not create overly large images in memory. Such large images can overflow the memory provided to the JVM (Java Virtual Machine). Care must be taken to provide the JVM with enough memory to manage the configured number of parallel workflows, with each having the potential to create an image at the maximum configured size.

InDesign (INDD) file format

If you intend to support the ingestion of INDD files so that you can generate dynamic rendition of this file format, you may want to review the following information before you create image presets.

For InDesign files, sub assets are extracted only if the Adobe InDesign server is integrated with AEM. Referenced assets are linked based on their metadata. InDesign Server is not required for linking. However, the referenced assets must be present within AEM before the InDesign files are processed for the links to be created between the InDesign files and the referenced assets.

If you intend to support the ingestion of INDD files so that you can generate dynamic rendition of this file format, you may want to review the following information before you create image presets.
See InDesign (INDD) file format.

To create an image preset:

In AEM, tap or click the AEM logo to access the global navigation console and tap or click the Tools icon and navigate to Assets > Image Presets.

Click Create. The Edit Image Preset window opens.

Примітка.

To make this image preset responsive, leave the width and height blank.

Enter values into the Basic and Advanced tabs as appropriate, including a name. The options are outlined in Image Preset options. Presets appear in the left pane and can be used on-the-fly with other assets.

Click Save.

Creating a Responsive Image Preset

To create a responsive image preset, perform the steps in Creating Image Presets. When entering the height and width in the Edit Image Preset window, erase the values and leave them blank.

Leaving them blank tells AEM that this image preset is responsive. You can adjust the other values as appropriate.

Примітка.

In order to see the URL and RESS buttons when applying an image preset to an asset, the asset must be published.

Image Preset Options

When you create or edit image presets, you have the options described in this section. In addition, Adobe recommends some best practice options to start.

Image Preset Best Practices

Adobe recommends these “best practice” option choices to start:

Format (Basic tab)- Select JPEG or another format that meets your requirements. All web browsers support the JPEG image format; it offers a good balance between small files sizes and image quality. However, JPEG format images use a lossy compression scheme that can introduce unwanted image artifacts if the compression setting is too low. For that reason, Adobe recommends setting the compression quality (on the slider) to 75. This setting offers a good balance between image quality and small file size.

Basic tab options

Field

Description

Name

Enter a descriptive name without any blank spaces. Include the image-size specification in the name to help users identify this Image Preset.

Width and Height

Enter in pixels the size at which the image is delivered. Width and height must be larger than 0 pixels. If either value is 0, then no preset is created. If both values are blank, a responsive image preset is created.

Format

Choose a format from the menu.

Choosing JPEG offers the following additional options:

Quality - Controls the JPEG compression level. This setting affects both file size and image quality. The JPEG quality scale is 1–100. Scale is visible when you drag the slider.

Enable JPG Chrominance Downsampling - Because the eye is less sensitive to high-frequency color information than high-frequency luminance, JPEG images divide image information into luminance and color components. When a JPEG image is compressed, the luminance component is left at full resolution, while the color components are downsampled by averaging together groups of pixels. Downsampling reduces the data volume by one half or one third with almost no impact on perceived quality. Downsampling is not applicable to grayscale images. This technique reduces the amount of compression useful for images with high contrast (for example, images with overlaid text).

Compression - Select a compression algorithm. Algorithm options for PDF are None, Zip, and Jpeg; for TIFF are None, LZW, Jpeg, and Zip; and for TIFF with Alpha are None, LZW, and Zip.

Choosing PNG, PNG with Alpha, or EPS provides no additional options.

Sharpening

Select the Enable Simple Sharpening option to apply a basic sharpening filter to the image after all scaling takes place. Sharpening can help compensate for blurriness that can result when you display an image at a different size.

Select Sharpen to apply a basic sharpening filter to the image after all scaling takes place. Sharpening can help compensate for blurriness that can result when you display an image at a different size.

Select Unsharp mask to fine-tune a sharpening filter effect on the final downsampled image. You can control intensity of effect, radius of the effect (measured in pixels) and a threshold of contrast that will be ignored. This effect uses the same options as Photoshop’s “Unsharp Mask” filter.

In Unsharp Mask, you have the following options:

Amount - Controls the amount of contrast applied to edge pixels. The default is 1.0. For high-resolution images, you can increase it to as high as 5.0. Think of Amount as a measure of filter intensity.

Radius - Determines the number of pixels surrounding the edge pixels that affect the sharpening. For high-resolution images, enter from 1 through 2. A low value sharpens only the edge pixels; a high value sharpens a wider band of pixels. The correct value depends on the size of the image.

Threshold - Determines the range of contrast to ignore when the unsharp mask filter is applied. In other words, this option determines how different the sharpened pixels must be from the surrounding area before they are considered edge pixels and are sharpened. To avoid introducing noise, experiment with values between .02 and 0.2.

Apply to - Determines whether the unsharpening applies to each color or brightness.

Sharp2 - Can produce slightly sharper results than Bi-Cubic, but at an even higher CPU cost.

Each Color and Brightness - each method can be based on color or brightness. By default Each Color is selected.

Print resolution

Select a resolution for printing this image; 72 pixels is the default.

Image Modifier

Beyond the common image settings available in the UI, Dynamic Media supports numerous advanced image modifications that you can specify in the Image Modifiers field. These parameters are defined in the Image Server Protocol command reference.

Important: The following functionality listed in the API is not supported:

Defining Image Preset Options with Image Modifiers

In addition to the options available in the Basic and Advanced tabs, you can define image modifiers to give you more options when defining image presets. Image Rendering relies on the Scene7 image rendering API and are defined in detail in the HTTP Protocol Reference.

The following are some basic examples of what you can do with image modifiers.